The prosecution case against Ms Knox was as flawed as hell and if this had happened in my country it's unlikely that she would even have been charged, let alone convicted.
The evidence against her was mostly circumstantial, eg: the DNA on the knife.
She retracted her confession, but that is easy to do. The problem was (and I haven't seen the confession, all I know is the way in which it has been reported)that a lot of her original confession dovetailed with much of the circumstantial evidence against her, and her subsequent statements didn't really stand up under scrutiny.
She did lie to the police and her demeanour was suspicious, but that in itself is not enough to convict.
Frankly, there wasn't a lot of hard forensic evidence and as I said, it wouldn't get past the CPS here, in my opinion. Unfortunately, the crime wasn't committed here. It was committed in Italy and it is their judicial system that tried the case. I personally don't like it and I would be extremely worried if I were an innocent party facing that kind of legal process.
However, Ms Knox did herself a lot of no good with her conduct. She may have done herself a few more favours if she had not appeared so blase about the whole thing. If she had appeared contrite..... humble.... respectful.
Rather, she made it easy for the prosecution to present her as a promiscuous drugs abuser who was cocky, arrogant and showed no remorse at the death of an innocent woman. If you put all the various factors into the mix of a murder committed in pursuance of a violent sex game that the victim did not want to participate in, then frankly, she did half the prosecution's work for them.
I don't know if she was guilty or not. I haven't seen the evidence. All I know is what I have read in the papers, like all of us here......... and depending where you read your papers, your view may differ from mine.